Apple Data Scientist interview questions

Very difficult system design interview. Two questions - one leetcode, one more system design heavy. Interviewer wasn't too friendly, and cut me off before time. Leetcode was a leetcode easy, so not too bad.

4 round interview in total for supply demand management (data scientist): Round 1: HR phone screening Round 2: Peer behavioural questions in English Round 3: Case study + presentation + coding test Round 4: Director interview